The present invention relates to a head lamp system of a vehicle. In particular, the invention relates to a head lamp system which has a discharge lamp, or a xenon arc lamp which is abbreviated as HID. A head lamp system using a discharge lamp is a promising future endeavor.
Conventionally, a head lamp system uses a filament lamp in the form of a projector type head light system or a multi-reflector type head light system. The lamp comprises a halogen lamp (iodine lamp) which is almost a point light source, and a reflector mounted around the lamp. Typically, a conventional filament lamp consumes 35-60 watts, and radiates 20 lumen/watt.
A conventional projector type head light system has two technical standards, PE (polyellipsoid), and DE (three dimensional ellipsoid). A conventional projector type head light system has a technical standard MS (multi surface).
A halogen lamp used in a conventional head light system operates with low power voltage, for instance, 12 V or 24 V. Therefore, no specific insulation means is requested. The average life time of a prior halogen lamp is approximately 400 hours. Some of technical standards for a conventional halogen lamp, are H-1, HB-1, H-4, HB-4, HB-5 and H-7. Each of the standards has a related technical standard for a flange type base plate which is coupled with a lamp, and a base plate acceptor which carries a lamp.
Because of regulations, a head light must be switched to one of high beam mode which illuminates long distance and low beam mode which illuminates short distance. This switching is conventionally carried out in two manners.
The first one has a first lamp for high beam mode and a second lamp for low beam mode. In this example, the two lamps are mounted around a center of a reflector, and one of the lamps is selectively turned ON.
The other one includes, as shown in the technical standard H-4, a single halogen lamp having a first filament for high beam mode, and a second filament for low beam mode. The second filament is partially covered with a shade, so that one of the filaments is selectively turned ON. In high beam mode, only a first filament for high beam mode is turned ON. In low beam mode, only a second filament which is partially covered with a shade is turned ON so that a part of light is prevented by the shade.
A discharge lamp is promising for head lights of the future, and would substitute a conventional halogen lamp.
A discharge lamp operates with high power voltage, approximate 20000 volts, and radiates light beams with high efficiency. For instance, a discharge lamp could radiate light beams at 100 lumen xc2x115% /watt. Thus, a discharge lamp provides a beam twice as strong as that of a halogen lamp. A discharge lamp has the further advantage that power consumption is low, typically 35 watts. A discharge lamp has life time four times as long as that of a halogen lamp. Therefore, a discharge lamp saves energy, and is ideal for a head light of a vehicle.
The current applicant has proposed a Japanese patent laid open publication 57504/1995, in which a compatible base plate acceptor for both a conventional projector type halogen lamp and a discharge lamp is proposed. That base plate acceptor can be used with high operational voltage.
A head light for a vehicle must be capable of switching a beam between a high beam mode and a low beam mode.
However, it is impossible to mount two light sources in a single discharge lamp, as is the case of a conventional halogen lamp. Further, it is impossible to mount two discharge lamps in front of a reflector because of the small mounting area, structure of a reflector, and cost.
Further, a light source of a discharge lamp is smaller than that of a conventional halogen lamp. Therefore, when a discharge lamp substitutes a halogen lamp, a structure to remove glare is essential.
Although the Japanese patent laid open publication 57504/1995 proposed a compatible base plate acceptor used for a high voltage discharge lamps and a conventional projector type halogen lamp, it has no switching facility into high beam or low beam, and no glare stop.
An object of the present invention is to provide a new and improved head light system by solving the disadvantages and limitations of prior head light systems.
It is also an object of the present invention to provide a head light system for a discharge lamp, having a high beam mode, a low beam mode, and a glare stop structure.
The above and other objects are attained by a head light system having a discharge lamp as a light source comprising; a base plate for fixing said discharge lamp, a shade in half-cylindrical shape arranged close to said discharge lamp for partially shading light of said discharge lamp, and moving means for relatively moving one of said discharge lamp and said shade relative to the other.
Preferably, said moving means comprises a remotely controllable means.
Preferably, said discharge lamp is mounted on a base plate of the discharge lamp, said shade is fixed close to said discharge lamp, and means for rotating said base plate is provided.
Preferably, said moving means slides said shade along a longitudinal axis of said discharge lamp so that said shade shades upper half or lower half of said discharge lamp.
Preferably, said moving means slides said discharge lamp, and said shade which shades said discharge lamp partially is fixed to a base plate.
Preferably, said moving means comprises a solenoid and a spring.
Preferably, said moving means comprises a male screw driven by a stepping motor, and a female screw engaged with said male screw for linear movement of one of said discharge lamp and said shade.
Preferably, said base plate for said discharge lamp is compatible with a base plate of a conventional base plate for a halogen lamp.
Preferably, said shade has a glare top arrangement having alternate projection and recess at extreme end of said shade in longitudinal direction.